The goal of this proposal is to create immunotherapeutics based on two high-affinity, HIV-specific, soluble T cell receptors (TCRs) as targeting molecules for HIV-infected cells. These human-derived TCRs were selected based on their ability to recognize HIV peptide antigens as well as their known respective variants displayed by the infected cells. The TCRs, created in a single-chain format (scTCRs), will be equipped with cytokine IL-15/IL-15R1Su or the human immunoglobulin heavy chain IgG1 Fc domain, through genetic manipulation. These scTCR-based immuno-active molecules will be in a dimeric form to enhance binding to their targeted epitopes due to their increase in avidity. Under the specific aims of this Phase I proposal, these fusion molecules will be characterized to ensure that they retain their bi-functional activities. They will be further assessed for their ability to elicit cytotoxic activity against peptide-loaded antigen- presenting cells and HIV-infected CD4+ cells. Additionally, the pharmacokinetic properties of the molecules will be evaluated in humanized transgenic mice. These data will assist Altor in selecting potential TCR-based immunotherapeutic molecules for further pre-clinical and clinical development under the next phase of this project. Successful development of two TCR fusion proteins with different antigen-recognition capabilities will allow for a combined therapy designed to circumvent HIV escape variants and. broadly target HIV-infected cells. The ultimate objective of this project is to use the fusions as injectable therapeutics to mount robust, targeted, innate immune responses to eliminate HIV reservoirs in infected cells when patients are maintained at the minimal-residual-disease stage via current HAART regimens. This novel strategy targeting virally infected cells is markedly different from current approaches aimed primarily at suppressing HIV replication or infectivity. PUBLIC HEALTH RELEVANCE: This proposal is to create immunotherapeutics based on the use of two high-affinity, HIV- specific, soluble T cell receptors (TCRs) as targeting molecules for HIV-infected cells. These TCRs were selected based on their ability to recognize HIV peptide antigens as well as their known respective variants displayed by the infected cells. If successful, these scTCR-based immuno-active molecules will then be used in a passive immune therapy approach to stimulate targeted, potent, innate immune responses against HIV-infected cells. Our ultimate goal is to use these molecules to eliminate the HIV reservoir in infected patients.